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I don't think it's a big deal, benchmarks are just toy programs. Once you learn about the `--release` flag you never forget it for production-ready code.

C has -O3, why isn't it the default? Because it takes a lot more time to compile. So I think no optimizations by default is the best choice. And I think Rust should do the same, you will be compiling more things in non-release mode than in release mode.

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Compiling without optimizations is indeed the default in Rust, but we have seen such an unbelievably large number of people not realize that a `--release` option exists that there have been several debates regarding whether or not this should be changed. Instead we've stepped up our documentation, we've made the package manager tell you which mode it's compiling in, and we've made Cargo put the finished binaries in either a clearly-named `debug` or `release` directory... and yet still they crash upon our walls, waving benchmarks where Rust is seemingly three times slower than Ruby.

It may seem obvious to you and I that compilers have optimization levels, but consider how many people for whom Java, with no optimization level flags, is their only exposure to a manually-invoked compiler.

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